63 research outputs found
Metabolic arsenal of giant viruses: host hijack or self-use?
© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Belhaouari, D., De Souza, G., Lamb, D., Kelly, S., Goldstone, J., Stegeman, J., Colson, P., La Scola, B., & Aherfi, S. Metabolic arsenal of giant viruses: host hijack or self-use? ELife, 11, (2022): e78674, https://doi.org/10.7554/elife.78674.Viruses generally are defined as lacking the fundamental properties of living organisms in that they do not harbor an energy metabolism system or protein synthesis machinery. However, the discovery of giant viruses of amoeba has fundamentally challenged this view because of their exceptional genome properties, particle sizes and encoding of the enzyme machinery for some steps of protein synthesis. Although giant viruses are not able to replicate autonomously and still require a host for their multiplication, numerous metabolic genes involved in energy production have been recently detected in giant virus genomes from many environments. These findings have further blurred the boundaries that separate viruses and living organisms. Herein, we summarize information concerning genes and proteins involved in cellular metabolic pathways and their orthologues that have, surprisingly, been discovered in giant viruses. The remarkable diversity of metabolic genes described in giant viruses include genes encoding enzymes involved in glycolysis, gluconeogenesis, tricarboxylic acid cycle, photosynthesis, and ÎČ-oxidation. These viral genes are thought to have been acquired from diverse biological sources through lateral gene transfer early in the evolution of Nucleo-Cytoplasmic Large DNA Viruses, or in some cases more recently. It was assumed that viruses are capable of hijacking host metabolic networks. But the giant virus auxiliary metabolic genes also may represent another form of host metabolism manipulation, by expanding the catalytic capabilities of the host cells especially in harsh environments, providing the infected host cells with a selective evolutionary advantage compared to non-infected cells and hence favoring the viral replication. However, the mechanism of these genes' functionality remains unclear to date.Royal Society - David C. Lamb
Woods Hole Center for Oceans and Human Health - John J. Stegeman
National Institutes of Health (P01ES021923) - John J. Stegeman
National Science Foundation (OCE-1314642) - John J. Stegeman
Agence Nationale de la Recherche ("Investments for the Future" program Méditerranée-Infection 10-IAHU-03)
Djamal Brahim Belhaouari
Gabriel Augusto Pires De Souza
Philippe Colson
Sarah Aherf
Incomplete tricarboxylic acid cycle and proton gradient in Pandoravirus massiliensis: is it still a virus?
The discovery of Acanthamoeba polyphaga Mimivirus, the first isolated giant virus of amoeba, challenged the historical hallmarks defining a virus. Giant virion sizes are known to reach up to 2.3”m, making them visible by optical microscopy. Their large genome sizes of up to 2.5Mb can encode proteins involved in the translation apparatus. We have investigated possible energy production in Pandoravirus massiliensis. Mitochondrial membrane markers allowed for the detection of a membrane potential in purified virions and this was enhanced by a regulator of the tricarboxylic acid cycle but abolished by the use of a depolarizing agent. Bioinformatics was employed to identify enzymes involved in virion proton gradient generation and this approach revealed that 8 putative P. massiliensis proteins exhibited low sequence identities with known cellular enzymes involved in the universal tricarboxylic acid cycle. Further, all 8 viral genes were transcribed during replication. The product of one of these genes, ORF132, was cloned and expressed in Escherichia coli, and shown to function as an isocitrate dehydrogenase, a key enzyme of the tricarboxylic acid cycle. Our findings show for the first time that a membrane potential can exist in Pandoraviruses, and this may be related to tricarboxylic acid cycle. The presence of a proton gradient in P. massiliensis makes this virus a form of life for which it is legitimate to ask the question âwhat is a virus?â
Family of Marseilleviridae : study of potential pathogenicity and description of pangenome
Marseilleviridae est une famille de virus gĂ©ants isolĂ©s initialement Ă partir de prĂ©lĂšvements environnementaux, dont Marseillevirus est le membre fondateur. La prĂ©sence des marseillevirus chez lâHomme a Ă©tĂ© dĂ©montrĂ©e dans quelques Ă©tudes. Les objectifs sont de mieux documenter la prĂ©sence des marseillevirus chez lâHomme, de modĂ©liser lâinfection par Marseillevirus chez la souris, et enfin, de dĂ©crire les gĂ©nomes des marseillevirus. Nous rapportons un cas dâinfection par Marseillevirus chez une patiente atteinte dâun cancer des ganglions, soulevant la question dâun Ă©ventuel lien entre Marseillevirus et cancer, Ă lâinstar de lâassociation existant entre dâautres virus et les cancers. Lâinfection des souris par Marseillevirus montre que celui-ci persiste un mois au niveau des «amygdales», confirmant le portage pharyngĂ© chronique observĂ© chez un deuxiĂšme patient. Enfin, nous identifions deux nouveaux groupes au sein de la famille, soulignant lâimportante diversitĂ© gĂ©nĂ©tique de la famille.Marseilleviridae is a new family of giant viruses primarily isolated from environmental samples and whose Marseillevirus is the founding member. The presence of marseilleviruses in humans has been demonstrated in few studies. The aims are to better document the presence of marseilleviruses in humans, to develop a model of infection of mice with Marseillevirus, and to describe the genomes of marseilleviruses. We report a first caes of infection by Marseillevirus in apatient with a lymph nodes cancer, raising the question of a potential link between Marseillevirus and cancer, as the well established association between some viruses and cancers. The infection of miceshows that Marseillevirus persist one month in the âtonsilsâ, confirming the chronic pharyngeal carriage reported in a second patient. Finally, we identify two new subgroups in the family, highlighting the considerable genetic diversity of the family
Epidémiologie moléculaire du virus de l'hépatite C
AIX-MARSEILLE2-BU Pharmacie (130552105) / SudocSudocFranceF
Marseillevirus in the Pharynx of a Patient with Neurologic Disorders
International audienceno abstrac
Hepatitis B Virus Genomics Knocking at the Door of Routine Diagnostic Laboratories
International audienc
The role of giant viruses of amoebas in humans.
International audienceSince 2003, dozens of giant viruses that infect amoebas (GVA), including mimiviruses and marseilleviruses, have been discovered. These giants appear to be common in our biosphere. From the onset, their presence and possible pathogenic role in humans have been serendipitously observed or investigated using a broad range of technological approaches, including culture, electron microscopy, serology and various techniques based on molecular biology. The link between amoebal mimiviruses and pneumonia has been the most documented, with findings that fulfill several of the criteria considered as proof of viral disease causation. Regarding marseilleviruses, they have been mostly described in asymptomatic persons, and in a lymph node adenitis. The presence and impact of GVA in humans undoubtedly deserve further investigation in medicine
Asfarviruses and Closely Related Giant Viruses
Acanthamoeba polyphaga mimivirus, so called because of its âmimicking microbeâ, was discovered in 2003 and was the founding member of the first family of giant viruses isolated from amoeba. These giant viruses, present in various environments, have opened up a previously unexplored field of virology. Since 2003, many other giant viruses have been isolated, founding new families and taxonomical groups. These include a new giant virus which was isolated in 2015, the result of the first co-culture on Vermamoeba vermiformis. This new giant virus was named âFaustovirusâ. Its closest known relative at that time was African Swine Fever Virus. Pacmanvirus and Kaumoebavirus were subsequently discovered, exhibiting phylogenetic clustering with the two previous viruses and forming a new group with a putative common ancestor. In this study, we aimed to summarise the main features of the members of this group of giant viruses, including Abalone Asfarvirus, African Swine Fever Virus, Faustovirus, Pacmanvirus, and Kaumoebavirus
Giant Viruses of Amoebas: An Update
International audienceDuring the 12 past years, five new or putative virus families encompassing several members, namely Mimiviridae, Marseilleviridae, pandoraviruses, faustoviruses, and virophages were described. In addition, Pithovirus sibericum and Mollivirus sibericum represent type strains of putative new giant virus families. All these viruses were isolated using amoebal coculture methods. These giant viruses were linked by phylogenomic analyses to other large DNA viruses. They were then proposed to be classified in a new viral order, the Megavirales, on the basis of their common origin, as shown by a set of ancestral genes encoding key viral functions, a common virion architecture, and shared major biological features including replication inside cytoplasmic factories. Megavirales is increasingly demonstrated to stand in the tree of life aside Bacteria, Archaea, and Eukarya, and the megavirus ancestor is suspected to be as ancient as cellular ancestors. In addition, giant amoebal viruses are visible under a light microscope and display many phenotypic and genomic features not found in other viruses, while they share other characteristics with parasitic microbes. Moreover, these organisms appear to be common inhabitants of our biosphere, and mimiviruses and marseilleviruses were isolated from human samples and associated to diseases. In the present review, we describe the main features and recent findings on these giant amoebal viruses and virophages
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